Known motor-driven rotary brushes include a brush comprising a cylinder from which bristles project. A heating element in conductive contact with the inside of the cylinder is electrically coupled via slip rings to a power supply extending through a handle of the brush. For satisfactory performance of such brushes it has been considered necessary that heat should be evenly distributed throughout the cylinder, and to this end a high degree of symmetry is typically provided, with widely dispersed bristles and external hair-engaging surfaces. To distribute heat more evenly in the axial direction the elements are elongated axially, as are arrays of bristles and external hair-engaging surfaces. Even circumferential heat distribution is provided by a centrally positioned heating element, with regularly circumferentially spaced bristles interspersed with external hair-engaging surfaces. The heat distribution also influences fits and tolerances, and where the cylinder may be an assembly compromising inner and outer tubes the prior art teaches that these should of like material, thus assuring that free rotation of the cylinder assembly is not adversely affected by differential expansion during heating.
However, while the brushing performance of these appliances is generally satisfactory, there remains a need for providing improved heating, curling or styling.
It would be advantageous to provide a brush that provides sufficient grip for hair to be readily, evenly wound up onto the cylinder when engaged with the free end of a tress, while avoiding the typical situation where the hair is so firmly bound on the bristles that brush rotation to roll up the hair causes uneven pulling of the hair, or even jamming of the rotation. Furthermore, there is a need for more energy efficient appliances. It is an object of the present invention to address the above needs or, more generally, to provide an improved hair brushing appliance.